Prevention of Noise Current Generation in Tin‐Based Lead‐Free Perovskites for Highly Sensitive Photodetection

• Published in: Advanced functional materials 2022-12, Vol.32 (51), p.n/a
• Main Authors: Jang, Woongsik, Kim, Kyusun, Kim, Byung Gi, Nam, Jeong‐Seok, Jeon, Il, Wang, Dong Hwan
• Format: Article
• Language: English
• Subjects: Bonding strength; Dark current; Iodine; Lead; lead‐free perovskites; Leakage; Materials science; Noise generation; noise suppression; Optoelectronics; Perovskites; Photodiodes; photoresponses; Tin; tin perovskites; Toxicity
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202207713

Lead (Pb) halide perovskites have attracted significant attention in the field of optoelectronics. However, due to the disadvantages associated with the presence of Pb in perovskite, its use should be minimized, if not completely eliminated. Herein, an efficient Pb‐free Sn‐based halide perovskite photodetector (PD) that is sensitive to visible and near‐infrared light is developed. The Sn perovskite is characterized with low toxicity and a narrow bandgap, and exhibits lower shunt leakage and a higher built‐in potential compared with a Pb‐based perovskite. Also, the relatively stronger bond strength between Sn and iodine ions in comparison with that observed in the Pb‐based perovskite effectively prevents charge injections that are vulnerable to dark current suppression. The Sn‐based perovskite PD demonstrates a high signal‐to‐noise ratio (SNR) of 51.12 dB, as well as an excellent cut‐off frequency of 763 kHz. To the best knowledge, this device is one of the fastest and most efficient photodiode‐type Sn‐based perovskite PDs developed to date. Unlike the Pb‐based perovskite device, the Sn‐based perovskite PD retains its high SNR over time. This effect may be attributed to the low movement of ion vacancies and degree of vertical shunt leakage in the perovskite material. Non‐toxic Pb‐free Sn‐based perovskite thin‐films display greater potential as photodetectors than photovoltaics. The fabricated photodiode‐type Sn‐based perovskite photodetector demonstrates a three‐fold higher specific detectivity, with a wider detection range and faster responses, than a conventional Pb‐based perovskite photodetector. These effects are attributed to the intrinsically narrower bandgap, smaller grain size, and reduced ion migration properties of Sn‐perovskites.